Add support for OCP protocol

Documentation/userspace-api/ioctl/ioctl-number.rst

@@ -412,4 +412,5 @@ Code  Seq#    Include File                                             Comments
                                                                        <mailto:naveenkrishna.chatradhi@amd.com>
 0xFD  all    linux/dm-ioctl.h
 0xFE  all    linux/isst_if.h
+0xFF  00-0F  uapi/linux/ocp_svsm.h
 ====  =====  ========================================================= ================================================================

arch/x86/coco/sev/core.c

@@ -1395,6 +1395,11 @@ static struct platform_device tpm_svsm_device = {
 	.id		= -1,
 };
 
+static struct platform_device ocp_svsm_device = {
+	.name		= "ocp-svsm",
+	.id		= -1,
+};
+
 static int __init snp_init_platform_device(void)
 {
 	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
@@ -1407,6 +1412,10 @@ static int __init snp_init_platform_device(void)
 	    platform_device_register(&tpm_svsm_device))
 		return -ENODEV;
 
+	// TODO: add probe like above
+	if (platform_device_register(&ocp_svsm_device))
+		return -ENODEV;
+
 	pr_info("SNP guest platform devices initialized.\n");
 	return 0;
 }

arch/x86/coco/sev/svsm.c

@@ -360,3 +360,72 @@ bool snp_svsm_vtpm_probe(void)
 	/* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */
 	return call.rcx_out & BIT_ULL(8);
 }
+
+int snp_svsm_ocp_list_sources(u8 *bytes_buffer, u8 *name_buffer, u32 buf_size,
+			      u32 *bytes_returned, u32 *buf_size_required)
+{
+	struct svsm_call call = {};
+	int ret;
+
+	call.caa = svsm_get_caa();
+	call.rax = SVSM_OCP_CALL(SVSM_OCP_LIST);
+	call.rcx = name_buffer ? __pa(name_buffer) : 0;
+	call.rdx = __pa(bytes_buffer);
+	call.r8 = buf_size;
+
+	ret = svsm_perform_call_protocol(&call);
+
+	if (ret < 0)
+		return ret;
+
+	*bytes_returned = call.r8_out;
+	*buf_size_required = call.r9_out;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snp_svsm_ocp_list_sources);
+
+int snp_svsm_ocp_read_source(u8 *buffer, u8 *name_buffer, u32 bytes_to_read,
+			     u32 offset, u32 *bytes_read)
+{
+	struct svsm_call call = {};
+	int ret;
+
+	call.caa = svsm_get_caa();
+	call.rax = SVSM_OCP_CALL(SVSM_OCP_READ);
+	call.rcx = __pa(name_buffer);
+	call.rdx = __pa(buffer);
+	call.r8 = bytes_to_read;
+	call.r9 = offset;
+
+	ret = svsm_perform_call_protocol(&call);
+
+	if (ret < 0)
+		return ret;
+
+	*bytes_read = call.r8_out;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snp_svsm_ocp_read_source);
+
+int snp_svsm_ocp_write_source(u8 *buffer, u8 *name_buffer, u32 bytes_to_write,
+			      u32 offset, u32 *bytes_written)
+{
+	struct svsm_call call = {};
+	int ret;
+
+	call.caa = svsm_get_caa();
+	call.rax = SVSM_OCP_CALL(SVSM_OCP_WRITE);
+	call.rcx = __pa(name_buffer);
+	call.rdx = __pa(buffer);
+	call.r8 = bytes_to_write;
+	call.r9 = offset;
+
+	ret = svsm_perform_call_protocol(&call);
+
+	if (ret < 0)
+		return ret;
+
+	*bytes_written = call.r8_out;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snp_svsm_ocp_write_source);

arch/x86/include/asm/sev.h

@@ -435,6 +435,11 @@ struct svsm_call {
 #define SVSM_VTPM_QUERY			0
 #define SVSM_VTPM_CMD			1
 
+#define SVSM_OCP_CALL(x) ((5ULL << 32) | (x))
+#define SVSM_OCP_LIST 0
+#define SVSM_OCP_READ 1
+#define SVSM_OCP_WRITE 2
+
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 
 extern u8 snp_vmpl;
@@ -528,6 +533,12 @@ void snp_msg_free(struct snp_msg_desc *mdesc);
 int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req);
 
 int snp_svsm_vtpm_send_command(u8 *buffer);
+int snp_svsm_ocp_list_sources(u8 *bytes_buffer, u8 *name_buffer, u32 buf_size,
+			      u32 *bytes_returned, u32 *buf_size_required);
+int snp_svsm_ocp_read_source(u8 *buffer, u8 *name_buffer, u32 bytes_to_read,
+			     u32 offset, u32 *bytes_read);
+int snp_svsm_ocp_write_source(u8 *buffer, u8 *name_buffer, u32 bytes_to_write,
+			      u32 offset, u32 *bytes_written);
 
 void __init snp_secure_tsc_prepare(void);
 void __init snp_secure_tsc_init(void);
@@ -636,6 +647,24 @@ static inline void snp_msg_free(struct snp_msg_desc *mdesc) { }
 static inline int snp_send_guest_request(struct snp_msg_desc *mdesc,
 					 struct snp_guest_req *req) { return -ENODEV; }
 static inline int snp_svsm_vtpm_send_command(u8 *buffer) { return -ENODEV; }
+static inline int snp_svsm_ocp_list_sources(u8 *bytes_buffer, u8 *name_buffer,
+					    u32 buf_size, u32 *bytes_returned,
+					    u32 *buf_size_required)
+{
+	return -ENODEV;
+}
+static int snp_svsm_ocp_read_source(u8 *buffer, u8 *name_buffer,
+				    u32 bytes_to_read, u32 offset,
+				    u32 *bytes_read)
+{
+	return -ENODEV;
+}
+static int snp_svsm_ocp_write_source(u8 *buffer, u8 *name_buffer,
+				     u32 bytes_to_write, u32 offset,
+				     u32 *bytes_written)
+{
+	return -ENODEV;
+}
 static inline void __init snp_secure_tsc_prepare(void) { }
 static inline void __init snp_secure_tsc_init(void) { }
 static inline void sev_evict_cache(void *va, int npages) {}

drivers/char/Kconfig

@@ -397,4 +397,14 @@ config ADI
 	  and SSM (Silicon Secured Memory).  Intended consumers of this
 	  driver include crash and makedumpfile.
 
+config OCP_SVSM
+	tristate "SNP SVSM OCP interface"
+	depends on AMD_MEM_ENCRYPT
+	default m
+	help
+	  This is a driver for the AMD SVSM	OCP protocol that a SEV-SNP guest
+	  OS can use to retrieve or configure state information of the Secure
+	  VM Service Module (SVSM) in the guest context. To compile this
+	  driver, choose M here.
+
 endmenu

drivers/char/Makefile

@@ -43,3 +43,5 @@ obj-$(CONFIG_PS3_FLASH)		+= ps3flash.o
 obj-$(CONFIG_XILLYBUS_CLASS)	+= xillybus/
 obj-$(CONFIG_POWERNV_OP_PANEL)	+= powernv-op-panel.o
 obj-$(CONFIG_ADI)		+= adi.o
+
+obj-$(CONFIG_OCP_SVSM)		+= ocp_svsm.o